March updates

Not a good couple of weeks for the robot the torso was to unstable the robot was in danger of tipping over. then the main computer failed long story short i replaced the it with a new I7 main computer. that works much better the WIFI is only 5 but still works. the battery charger started to fail resulting in a shorter run time. the new charger gives a 2 hour run time now. Navigation is starting to head in the right direction. we still get stuck in tight spots we have achieved a few way point navs.

A few thoughts

• charging system needs beefing up we are having wire power loss
• add in the 3rd battery for a extra 18AH
• start navigation tuning with a new map
• see how a boost charge affects run time

using a LLM with vscode has made tuning the robot easier

networks and bugs

 

For the last couple of months I have been chasing bugs first the network was slow which made the robot uncontrollable I switched out the I5 for a RPI5 but had to add a UPS to give the RPI enough power. Better but not enough I switched the middle ware to Zenoh but that required a upgrade to ROS2 Jazzy and Ubuntu 24.4 it soon became apparent that the RPI5 didn’t have the speed to run the complete stack not even enough to run the robot and cameras. I replaced the WiFi in the I5 from a USB dongle to a express WiFi card so we we ran the network at the same speed as the RPI but I was getting packet drop I added a extra WiFi access point tied to the wired network the I5 went from 120 kbit/s to 300 mbit/s a big improvement, we can now run the robot with everything required running with very little lag. The next task was getting auto dock working to dock in reverse in the end it was simpler just to write my own node. With all the systems running on the robot I started having battery fails we replace the battery for the other robot but that didn’t last very long. A bit more digging the robot draws 4 amps for the moment we changed the way we operate by docking the robot between tasks. Now that only left Navigation to sort out after a few days of tuning and reading we adjusted the global cost map inflation to give smooth pathways and the velocity smoother to keep velocities that work with the robot. We can navigate around the house and it will work most of the time still more tuning required but that is for another day. We also started to add the covers on the robot now that we can navigate through door ways it time to put on the torso

 

 

 Robbie now with torso

I wanted to test the navigation system with the whole robot I'm looking at the acceleration profiles and how the robot handles doorways and corridors and just driving in general

 Docking Server

Here is a clip showing the nav2 docking server Robbie is docking forward so we can work on the other systems. I have mapped the un/dock sequence to the joystick this seems to make a good natural work flow. the undock should be called from the BT server before the start of navigation

 October update

Time for another update on robbie after changing the the drive base to the omni_bot base it showed potential but also a lot of short comings the base was to large to consistently go through corridors the structural integrity was compromised. The base was designed with tighter tolerances and greater rigidity also smaller. We now use stepper motors for the steering system with magnetic encoders. and I2C controller motor drivers with encoders . The motor drivers were from the old design and the python driver was a legacy design. The big change was the odometery function using wheel angles and wheel velocity coupled with a gyro, magnetometer that gave a 20cm accuracy after a 16 meter drive. The successful test of the new omometery node I was able to remover the dead encoder wheel and use ROS nav2 with a MPPI controller in OMNI mode using the nav2 docking server the auto dock works with greater reliability and comes with a undock function all this is mapped the joy stick controller. The python controller was starting to be a bottle neck so I rewrote it in CPP with a noticeable speed improvement. 

this is a video of the the base using navi2 to chase the videographer https://youtu.be/5DKG3iNSfLM

and some build photos

 

 

Intergrating Omni_bot and Robbie

I have merged the omni_bot base with the torso of Robbie

The integration of three omni wheels with encoders has significantly enhanced and simplified the robot's odometry. Precise measurements of wheel rotations from the encoders enable accurate localization and mapping of the environment, resulting in more reliable navigation.

By leveraging Nav2 and slam_toolbox for navigation, the robot benefits from powerful out-of-the-box navigation capabilities. These robust ROS packages facilitate autonomous path planning, obstacle avoidance, and efficient goal-reaching, minimizing the need for extensive modifications.

The adoption of the differential drive plugin for navigation has greatly reduced fishing motion in the Y-space, resulting in smoother and more fluid movement

Replacing the RPI4 with an I5 mini PC running Ubuntu 22.4 and ROS Humble significantly boosts computing power and reliability. The I5 mini PC offers faster processing speeds, improved multitasking capabilities, and better software compatibility, simplifying installation and ensuring a stable platform. Eliminating the Timing Issues by Centralizing Nodes on I5: Centralizing all nodes on the I5 mini PC resolves timing issues observed in the previous setup. Improved synchronization and coordination between nodes result in smoother communication and minimized delays, enhancing performance and responsiveness.

Autodock functionality now incorporates strafing moves, enabling precise alignment with the docking beacon. This refinement enhances the accuracy and efficiency of the docking process.

The low power monitor program has been enhanced to incorporate additional functionality. Utilizing a QR marker and the rear-facing camera, the robot can accurately rotate to the correct angle before initiating Autodock. This improvement ensures precise alignment and eliminates potential errors during docking.

Control and day-to-day operation of the robot are seamlessly achieved using the existing chat bot, which now supports custom commands. Unknown commands are recorded for further integration into AIML, continuously improving the system's understanding and response capabilities. Text-based input simplifies interaction, enabling smooth communication between users and the robot platform.

 

 

 

Robbie update

 I haven't done a update in a while Robbie now runs ROS2 humble on a single RPI4

ROS2 humble is at last at the same level as ROS1, but in general it works much better. Navigation is much more stable and works out of the box the ability to do mapping and use move_base at the same time makes mapping quicker. the work flow is now 

• start the robot , 
• launch slam and navigation 
• set points in RVIZ until the map is complete
• save the map in RVIZ

using the way point navigator feature in RVIZ you can set the way points you would

like the robot to traverse press run and the robot moves the course. very little effort required.